New roles for chemoreceptor paralogues in Drosophila

描述（由申请人提供）：本工作旨在以果蝇果蝇为模型，确定冷检测的分子机制。感觉系统在人类健康中起着关键作用。人类感觉系统功能障碍不仅与疾病有关，温度的检测对人类疾病媒介昆虫的生存和寻找宿主行为也很重要。目前，我们对昆虫温度检测的分子认识是有限的：昆虫冷受体尚未报道。我们的初步数据表明，两个亲电离性受体家族成员IR21a和IR25a参与冷感知。嗜离子受体（IRs）是无脊椎动物中iGluRs的一个亚家族（果蝇有66个IRs），已知不是作为谷氨酸依赖的突触传递的介质，而是作为酸和胺的化学受体。我们提议验证IR21a和IR25a的特定同工型通过作用于腹和/或唇瓣的冷传感器来驱动冷回避的假设。通过细胞特异性拯救实验，我们建议确定哪些IR21a和IR25a亚型介导冷回避，并测试这些ir在冷传感器中的表达是否是冷回避所必需的和/或必需的。我们还将测试IR21a和IR25a是否介导冷感测。利用钙成像和电生理学的结合，我们将通过检查缺乏这些蛋白质的突变体中每组冷传感器的冷反应如何改变，来检查IR21a和IR25a对冷感应的贡献。我还将测试IR21a和IR25a是否通过这些蛋白在苍蝇中的异位表达以及在青蛙卵母细胞和培养的哺乳动物细胞中的异源表达来形成冷受体。这些研究将有助于对冷接受的认识和鉴定

DESCRIPTION (provided by applicant): This work aims to identify the molecular mechanisms of cold detection, using the fruit fly Drosophila melanogaster as a model. Sensory systems play key roles in human health. Not only is human sensory system dysfunction associated with disease, the detection of temperature is important for the survival and host-seeking behavior of insect vectors of human disease. At present, our molecular understanding of temperature detection in insects is limited: insect cold receptors have not been reported. Our preliminary data suggest two Ionotropic Receptor family members, IR21a and IR25a, are involved in cold sensing. Ionotropic receptors (IRs) are a subfamily of iGluRs in invertebrates (Drosophila has 66 IRs) known to act not as mediators of glutamate- dependent synaptic transmission, but as chemoreceptors for acids and amines. We are proposing to test the hypothesis that specific isoforms of IR21a and IR25a drive cold avoidance by acting in the cold sensors of the arista and/or labellum. Using cell-specific rescue experiments, we propose to determine which IR21a and IR25a isoforms mediate cold avoidance, and to test whether expression of these IRs in cold sensors is necessary and/or required for cold avoidance. We will also test if IR21a and IR25a mediate cold sensing. Using a combination of calcium imaging and electrophysiology, we will examine the contribution of IR21a and IR25a to cold sensing by examining how the cold-responsiveness of each set of cold sensors is altered in mutants lacking these proteins. I will also test whether IR21a and IR25a act forming a cold receptor by ectopic expression of these proteins in the fly and by heterologous expression in frog oocytes and in cultured mammalian cells. These studies will contribute for the understanding of cold-reception and the identification of the receptors will be extremely significant to elucidate the molecular mechanisms involved.